Heretofore, magnetic recording media have been widely used for magnetic recording and reproduction which comprise non-magnetic supports and magnetic coatings applied thereto. The magnetic coatings contain ferromagnetic powders formed of needle crystals such as Co-containing magnetic iron oxide and CrO.sub.2 dispersed in binders.
Recently, there have been strong demands for improvements in recording density, and, as one proposal, conventional Co-containing magnetic iron oxide has also been divided more finely in efforts to achieve this object. This is, however, still insufficient to improve reproduced outputs of short wavelengths in high frequency regions. Magnetic layers using ferromagnetic alloy powders are considerably improved in reproduced output. However, when the magnetic layers using only ferromagnetic alloy powders are employed, there is the disadvantage that it is difficult to obtain adequate running durability.
In particular, a plate-like ferromagnetic hexagonal ferrite powder has recently been developed. Magnetic recording media using this ferromagnetic powder have the disadvantage that while the outputs of the short wavelengths on the high frequency side are high, the outputs of long wavelengths on the low frequency side is low.
In order to overcome these disadvantages, it was proposed to allow for a ferromagnetic barium-ferrite powder and a ferromagnetic .gamma.-Fe.sub.2 O.sub.3 powder to coexist (JP-A-57-212623, the term "JP-A" as used herein means an "unexamined published Japanese patent application"). However, it was difficult to obtain higher output by this method.
Further, the present inventors produced magnetic tapes by using the ferromagnetic alloy powder and the ferromagnetic hexagonal ferrite powder which were mixed with each other. However, no substantial improvement in reproduced output was observed.
In a system utilizing a wide band extending a low band to a high band, such as in video tape, a plural-magnetic layer structure is considered to be advantageous. Previously, various layer structures have been proposed. Namely, the output of the overall band can be improved by giving high band characteristics to an upper layer and giving low band characteristics to a lower layer.
In particular, in order to raise the reproduced output in the high frequency region, it is proposed to use acicular ferromagnetic oxide powders such as iron oxide Co-containing iron oxide and CrO.sub.2, and ferromagnetic acicular metal or alloy powders mainly comprising iron and having high coercive force and high saturation magnetization, as magnetic substances used in the upper magnetic layer. However, the ferromagnetic acicular metal or alloy powders utilize longitudinal magnetizing components, and therefore a significant decrease in reproduced output is encountered in the high frequency region, namely, in the short wavelength region in recording (for example, a wavelength of 0.5 .mu.m or less).
It is further proposed to use hexagonal ferromagnetic magnetoplumbite-ferrite powders such as barium-ferrite, as magnetic substances used in the upper magnetic layer (for example, JP-A-57-195329 and JP-A-60-223018).
The hexagonal ferromagnetic ferrite powders can utilize vertically magnetizable components. It is therefore believed that the characteristics thereof are superior to those afforded by the ferromagnetic acicular metal or alloy powders. Actually, the output at a recording wavelength of 0.5 .mu.m for these powders does exceed that of the acicular metal or alloy powders. However, the improvement still is not considered sufficient. Moreover, even when the thickness and magnetic characteristics of the plural-layer structure are suitably selected, the output in the recording wavelength region of about 1 to 4 .mu.m is not as excellent as compared to that of a single- or plural-layer tape using the ferromagnetic acicular metal or alloy powder.